The difference is the skills a racing sim enthusiast has would take literal years to cultivate even if you have the ability to learn it.
Here’s a guy who went to Spec Miata as his first exposure to racing other cars from a sim:
https://www.mazdamotorsports.com/2018/02/21/john-allen-trans...
To put into perspective how insane that is, at High Performance Driving events (non competitive events where you get to drive around a track), you might expect someone to move to the advanced group where you’re still not allowed to pass in turns, and have to be pointed by after multiple years!
Some places would actually require you to take a year's worth of events just to get into a group where passing is allowed at all without an instructor in the car
This guy went straight into full on Spec Miata with purpose built cars and full on passing for his first event!
That would be like someone playing baseball for the first time in Minor League Baseball, it takes some extremely real and difficult to develop skill to do so even if it isn’t MLB...